[Thorbrandr]

Went to mount a rail on the left, and found that there is "pad" on the left side of the receiver that keeps the rail from mounting flush. Looks like the pad is supposed to be on the receiver. Is this normal? What options are there for left side rails?

Thanks
Chris

 

[Thorbrandr]

Follow up...

I contacted Critical Dimensions. They stated it was probably a feature of my receiver, but offered to mill a relief cut in the rails. The other solution they offered was a set of washers.

As it turns out, even if the pad were not there, the sides of the receiver are not parallel to the sight/bore. There is about a .025” overall taper (side to side) on the receiver. That taper is probably good for 8-9” of windage error at 50 yards for laser if I did the math right.

So, I picked through the washers. I had one that was within a few .001” of the thickness necessary to put the rail in alignment with the sight.

I am really impressed with CD's customer support. Some people would have said “it’s your receiver”, and left it at that. Instead, they offered a number of solutions.

:? :?

 

[ShipWreck]

That's good to hear.

I looked at mine, and I couldn't figure out what you were referring to.

 

[cqbdriver]

I just got a PS90 a few weeks ago. It has the same pad. It is located on the rear screw hole. I attached a left rail, but I was only mounting a light & it worked fine for that. The bright spot of the light is right where the sight is pointed at CQB distance.

 

[M1P90]

:-? Very strange. Can someone post some picks of this pad?

Thanks

 

[cqbdriver]

This is not my rifle. I'll have to wait to get home to photo my rifle. However, this appears to be like mind.

Looking on the web, this doesn't appear to be anything new. When I was attaching my rail, it just didn't look right to have the rail resting on the pad & not flush

 

[cqbdriver]

Here's a photo of mine:

 

[Promoted Pawn]

hmm. That must irk you a little. I'm glad mine don't have that!

 

[blkbd]

I bought mine about a week and a half ago and just checked it and it has that little raised pad too.

 

[M1P90]

:-? :evil: Who the ....what the... Why the heck did they add that??????

Makes no scense to me... looks like my REM 2 will still slide into the sling slot but... that is just weird. :roll:

 

[Thorbrandr]

Yep, it is weird. I have to say it looks deliberate. The top of that pad is very smooth. While I go this PS90 new this is one of the models with the original white sight, so it is not the latest production.

The problem is that the taper in the receiver without the pad is enough to eat up a lot of windage correction for a laser. The Pad triples that amount.

Good news is that washer on the front fixed the alignment issue.

 

[Thorbrandr]

Forgot my manners - thanks for posting the pic! I haven't tried that yet.

That is exactly what is going on on mine, and I found a number on line showing that pad.

Seems like the rail makers may need to account for it. Hopefully the REM2 will mount up fine.

 

[CriticalDimensions]

From the best I can tell those receivers with the pads were originally produced with the intent to be P90's without the side rail threaded holes. When the receivers didn't meet mil-spec due to casting problems, like the taper mentioned, they were then made into PS90's and the threaded holes added without machining the pad for the clearance required for rail installation. Without an answer from FNH about these, there's no real way to know exactly why these paticular receivers exist. The 4 PS90's I have in house do not have the pad area or any taper in the side rail mount area.

P90